(1) Field of the Invention
The invention is related to a rope suspension device with at least one rope suspension module that is adapted for suspension of at least one rope from a rotorcraft, said rope suspension device comprising the features of claim 1.
(2) Description of Related Art
Rotorcrafts, and in particular helicopters, are commonly used for rappelling, extraction and insertion tasks during special helicopter operations using suitable ropes that are suspended from the helicopters. For instance, helicopters are used for rapidly descending, i.e. rappelling, of persons from a given height, for extracting persons from a given area and/or for inserting persons into a given area. Furthermore, helicopters are used in transportation and delivery of cargo, e.g. for military purposes or in the construction sector. More generally, helicopters can be used in any special operation that requires application of one or more ropes that are suspended from the helicopters.
Usually, the one or more ropes are suspended from the helicopters by means of associated rope suspension devices, which require a high degree of safety, in particular if human external cargo (HEC) is implied. Furthermore, designing and constructing such rope suspension devices requires the compliance with applicable safety regulations and specifications, such as the US-American Federal Aviation Regulations (FAR) and/or the European Certification Specifications (CS). For instance, according to FAR29/CS29 and FAR27/CS27, suspended ropes that are under tension in operation must be releasable until up to 3.5 times of an underlying rated load therefore and they must have a comparatively simple design to reach requested 10−9 safety requirements for HEC.
However, conventional rope suspension devices are usually not adapted for allowing a quick release of a suspended rope if the rope is under tension, due to a comparatively high reacting force on an underlying release mechanism. For instance, if the suspended rope is jammed under a stone or other item, a cabin operator within the helicopter is needed for cutting the rope by means of a knife. Nevertheless, e.g. in a rescue situation, a helicopter may not provide a sufficiently stable platform and in case of winds or gust there is a high risk for injury of the cabin operator when trying to cut the rope with the knife.
The document U.S. Pat. No. 5,158,247 B1 describes a rope suspension device for a helicopter that comprises a beam fixed to the helicopter floor or roof in the vicinity of an opening. Ropes for the lowering to the ground of persons are attached to bolts by rings. The operation of a handle makes it possible to simultaneously and instantaneously release or jettison all the ropes by pivoting a clasp into each of the bolts in opposition to a spring. For this purpose the handle simultaneously operates pivoting latches, which cooperate with the clasps by complimentary cam surfaces. More specifically, each clasp is mounted so as to pivot for applying the forces that are induced by an end ring of a given rope to the clasp, which is substantially the direction of the end of the rope connected to the ring, when said rope is made taut by a load that it carries. In this case, it would not be possible for the clasp to open under the stresses of the loaded rope, because the force exerted by the ring against the clasp can in no case stress the latter in the opening direction.
However, this means that in this rope suspension device an application of force along the rope in a direction that points away from the rope suspension device strongly pivots the clasp towards its closed position, so that a required actuation force for activating, i.e. operating the handle would be so high, that it would not be possible for an operator to release the rope. Thus, an easy and quick release of the rope under any foreseeable condition is not guaranteed, especially if the 3.5 g and a safety factor of 1.5 according to the latest certification requirements according to FAR29/CS29 and FAR27/CS27 are applied. Furthermore, this rope suspension device is comparatively complex and requires a multiplicity of constituent components, each of which could at least in part cause an unintended opening of the rope suspension device in case of a failure.
The document U.S. Pat. No. 6,948,586 B1 describes a quick rope release device that can be used by persons in rapidly descending from a helicopter using a rope and then quickly disengaging from the rope. This quick rope release device comprises a body having a rim which defines a rope opening therein. The body is further adapted to be affixed to a harness. A lock extends across the rope opening. The lock frictionally engages a rope extending through the rope opening. A retracting mechanism manually releases the lock from engagement with the rope. The retracting mechanism is biased to a secured position, whereby the lock is engaged with the rope. The retracting mechanism, when actuated, manually releases the lock to an open position, whereby the rope is quickly released from the lock.
However, this quick rope release device is not installed in the helicopter, but on the harness, which is close to the person on the rope. Thus, if the rope is e.g. jammed under a stone or other item, it cannot be released quickly from within the helicopter and a cabin operator within the helicopter is again needed for cutting the rope by means of a knife.